Electric arc furnace dust (hereinafter "EAF dust") is produced by the steel industry and on a rough basis is classified into two major categories. One category is dust which is produced from steel mills and the other is dust which is produced from steel foundries. Typically EAF dust is obtained in "bag houses" but other means to minimize dust emission may also be used such as cyclones and electrostatic precipitators and the like and the dust collected therein may be used in a similar manner.
In the United States EAF dust produced in steel mills has been classified under Resource Conversion and Recovery Act because of the presence of leachable lead and cadmium components. Consequently, the disposal problems which are associated with disposing EAF dust are sizeable and the costs exact a heavy burden on the steel industry. Because typically electric arc furnaces are being used when processing scrap metals and to a lesser degree sponge iron and the like, the consistency of EAF dust components may vary fairly radically and the control thereof is fairly difficult to maintain. Thus, components such as zinc and other metals are present in EAF dust. These components may vary widely and are difficult to control unless the entire dust load is mixed so as to disperse uniformly the various components from fairly numerous mill runs.
Although, a number of methods have been used to extract from EAF dust valuable components, e.g. zinc, a far simpler and more economically attractive method has been to utilize the by- product in its raw state. Even after the recovery of some of the metals from EAF dust the disposal problem is still present and, therefore, the disposal costs have to be taken into account in any Return-on-Investment (ROI) analysis when considering EAF dust produced from steel mills. An alternative for disposing EAF dust is to devise a properly sanctioned land disposal site or treat the EAF dust for stabilizing or encapsulating the component parts thereof and then disposing the stabilized mass in a suitable land disposal site.
With respect to the stabilized--encapsulated mass the added process steps and added cost consideration render the processing of EAF dust and the various component metals therein a difficult task and again penalizes any arc furnace operation.